Voltmeter vs. Ammeter

[Stuart+2]

Please pardon my lack of knowledge, but why is a voltmeter the best instrument for monitoring an alternator while an ammeter is best for a generator?

They both ultimately put out D.C. so I'm missing something!

Thanks

[neilsjuke]

You can use both but due to the size of the wiring a volt meter just needs volts to work an ampmeter needs the current to work ie large wires to take the load/charge.
Neil

[lotusanglia1965]

You generally use ammeter with dynamo as they are often borderline on output,so you can monitor charge/discharge. alternators normally just work or don't! so voltmeter is adequate.

[neilsjuke]

Alternators can have Faults when the current output is half but the voltage is ok you need a ampmeter to show this.it's the dynamo that tends to work or not . Dynamo are very reliable but only if they are not bodged or the regulators adjusted to the correct settings.
Neil

[ppnelan]

If an ammeter fails, you lose your electrics...
If a voltmeter fails, you don't
The ignition warning light will tell you when there's a (dis)charging problem.

Matthew

[neilsjuke]

With a Alternator the w/light only tell you that the Alt has reached the same voltage as the battery not that it is supplying amps .never seen an ampmeter go open circit.

[GrUmPyBoDgEr]

I always found that the Ameter was a very good indicator for a broken fan belt. It goes into discharge before the temperarure guage goes over the top.
John

[Stuart+2]

Thanks to all - much enlightened.

[Frank Howard]

I have upgraded my car to an alternator. I wanted to add either an ammeter or a volt meter but couldn't decide. I checked my friend's +2 which came from the factory with an alternator and it had an ammeter. My Europa Special came from the factory with an alternator and it had an ammeter also. So I chose an ammeter because I thought it would be the most "period correct" instrument. Now everyone tells me that in light of the fact that I have an alternator, I should have gone with a volt meter. Oh well...

[neilsjuke]

Alternators can have Faults when the current output is half but the voltage is ok you need a ampmeter to show this.it's the dynamo that tends to work or not . Dynamo are very reliable but only if they are not bodged or the regulators adjusted to the correct settings.
Neil

You went the best way
Neil